1. Field of the Invention
The present invention relates generally to methods of determining a mid-stroke position of an active material actuated load, and more particularly, to methods of determining the mid-stroke position by inducing a change in electrical resistance in the actuator through a change in the mechanical resistance to motion or otherwise modifying a circuit, correlative to the position during the stroke.
2. Discussion of the Prior Art
Active material actuators are used in a variety of applications to translate a load between first and second generally predetermined positions corresponding to the available strain or shape memory of the material, so as to define a “stroke.” In many instances, however, determining at least one mid-stroke position is also beneficial and desirous. For example, where translating a load between first and second stages of an assembly process, it may be desirous to detect when the load is midway between stages, so as to pre-initiate the second stage of the process. Conventional methods of determining mid-stroke positions of translated loads, generally include various types of position sensors and other external devices that are configured to track and/or selectively engage the load. These methods present various concerns in the art, including added mechanical complexity, higher cost, greater packing requirements, increased weight, and more components, especially where the load is large and/or cumbersome.